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Data & Statistics on Fragile X Syndrome

Fragile X syndrome (FXS) is the most common known cause of inherited intellectual disability.1FXS affects both males and females. Females often have milder symptoms than males.2The exact number of people who have FXS is unknown, but it has been estimated that about 1.4 per 10,000 males and 0.9 per 10,000 females have FXS.3

Among people affected with FXS, intelligence quotient (IQ) scores decline noticeably with age: adolescents and adults consistently score lower on IQ tests than young children.4

Young children with FXS often take longer than their peers without FXS to reach early language milestones and to develop nonverbal communication (communication without words, typically through gestures, facial expressions, and body language).4

While the average IQ score of the general population is 100, boys with FXS have an average IQ score under 55.4

Diagnosis

The average age of FXS diagnosis for boys is 35 to 37 months. Girls are diagnosed at an average age of 42 months.5[Read article]

Aggressive/disruptive behavior was the only behavior treated with medicine more often in individuals with both FXS and ASD compared to those with just FXS. About 4 in 10 individuals with both FXS and ASD were treated with medicine for aggressive/disruptive behavior compared with less than 2 in 10 individuals with FXS alone.

Compared to children who only have ASD, children with both FXS and ASD may be less likely to receive Behavior Therapy.

About 4 in 10 women with FXS achieved a high or very high level of independence in adult life compared to about 1 in 10 men.

About 4 in 10 women with FXS lived independently, often with a spouse or romantic partner, compared to 1 in 10 men who lived independently, and rarely with a spouse or romantic partner.

About 8 in 20 women with FXS required no assistance with activities of daily living compared to 1 in 20 men.

The majority of women with FXS had at least a high school diploma; the majority of men did not have a high school diploma.

Almost half of women with FXS had full-time jobs, compared to 2 in 10 men.

Premutation

People with a fragile X premutation do not have fragile X syndrome but might have another fragile X-associated disorder. Some people with fragile X premutations have noticeable symptoms, and others do not.

The exact number of people who have a fragile X premutation is unknown. Studies estimate that between 1 in 148 and 1 in 291 females and 1 in 290 and 1 in 855 males in the United States may have a fragile X premutation.12-17

These numbers are important because both men and women are at risk for having symptoms related to fragile X-associated disorders.13[Read article]

Women with a premutation reported their last menstrual cycle at an earlier age (on average, 48 years) than women without a premutation (on average, 51 years).

Men and women with a premutation were more than four times as likely to report dizziness or fainting and more than twice as likely to report numbness compared to people without a premutation.

People with a premutation are almost twice as likely to have a child with a disability as people without a premutation.13[Read article]

A national parent survey found that males and females with fragile X premutation were more likely to have been diagnosed or treated for other conditions that occur together with FXS compared to people who did not have a premutation.7[Read scientific summary]

Costs

A study analyzing the employment impact and financial burden experienced by families of children with FXS found that18[Read scientific summary]

With each additional condition occurring with FXS, there was greater financial burden for the family.

About half of families reported that FXS caused a financial burden.

In more than 6 in 10 families, parents changed work hours, stopped working, or turned down a job because of having a child with FXS.

Families reported that therapies accounted for about one-third of their FXS-related out-of-pocket expenses. An additional third of out-of-pocket expenses went to medicines and other medical costs, including genetic testing and developmental evaluations.